The home and auto lender received $17.3 billion of state funding and Jim Millstein, the US Treasury's chief restructuring officer, advised GMAC last month that it should carry out an initial public offering to help repay its debts.
According to a source close to the deal, Goldman Sachs and Citigroup have been brought on board by GMAC as it investigates what avenues it can take to raise the funds.
While the agreement has not been confirmed by any of the three companies, a GMAC spokesman told Bloomberg: "GMAC is committed to repaying the American taxpayer in full."
Citigroup repaid its own TARP debt of $20 billion by carrying out a stock issue last December.
However, the government still has a 27 per cent share in the bank, a stake that was agreed as part of the total $45 billion Citigroup received in bailout funding.
By Asim Shah